The Crystal Structure and Phase Transition of Hf2Pt3

• Published in: Journal of phase equilibria and diffusion 2013-10, Vol.34 (5), p.385-389
• Main Authors: Stalick, J. K., Wang, Ke, Waterstrat, R. M.
• Format: Article
• Language: English
• Subjects: Ceramics; Composites; Crystallography and Scattering Methods; Engineering Thermodynamics; Glass; Heat and Mass Transfer; Metallic Materials; Natural Materials; Physics; Physics and Astronomy; Thermodynamics
• ISSN: 1547-7037; 1863-7345
• DOI: 10.1007/s11669-013-0247-9

The structure of Hf 2 Pt 3 has been re-investigated using transmission electron microscopy and Rietveld refinement of neutron powder diffraction data at temperatures up to 1500 °C. This compound does not belong to the MoSi 2 structure type as previously reported, but instead is isostructural with Ti 2 Pd 3 and the low-temperature form of Ti 2 Ni 3 . The crystal structure is orthorhombic (pseudo-tetragonal), Cmcm , Z  = 4, with a  = 14.653(1) Å, b  = 4.8741(3) Å, and c  = 4.8671(3) Å at room temperature. The b/c ratio decreases from 1.0014(2) at room temperature to 1.0005(3) at 1500 °C, but the material does not transform to the high-temperature form of Ti 2 Ni 3 ( I 4/ mmm ) under the conditions studied. The electron diffraction data indicate multiple stacking faults as well as short-range order. On heating above 1630 °C there is a phase transition to a B2-related structure with a  ≈ 3.315(1) Å at 1659 °C.